The Pharmocokinetics Research Laboratory at San Francisco General Hospital supports clinical research projects described in this proposal and is a core support unit for other components of the Drug Dependence Clinical Research Program Project Grant DA01696. Specific research proposals include the following: (1) Studies of the effects of liver disease on the bioavailability and pharmacologic effects of the narcotic analgesics meperidine, pentazocine and methadone; (2) studies of interactions of methadone with phenytoin and diazepam in methadone maintained patients; (3) studies of the pharmacokinetics and metabolism of methadone in methadone maintained pregnant addicts during various phases of pregnancy and postpartum; (4) studies of interactions of nicotine and tobacco with cannabinoids and alcohol; (5) studies of the pharmacokinetics and pharmacology of cotinine, the major metabolite of nicotine and nornicotine, the second most plentiful tobacco alkaloid.